1. Field of the Invention
The present invention relates to an arrangement of an excavating chain for conveying ballast of a track bed extending in a first plane, the excavating chain being comprised of a succession of linked chain links and being driven in a second plane inclined with respect to the first plane in an operating stage, and a guide wherein the excavating chain is guided, the guide comprising a transverse guide section positioned in a line of intersection of the first and second planes, in the operating stage, and longitudinal guide sections, the longitudinal guide sections being connected to ends of the transverse guide section by joints having a vertical axis and the guide sections defining a guide channel for the excavating chain, the guide channel being defined by a lower glide track and an upper glide track extending parallel to the second plane and an end glide track extending perpendicularly to the second plane, the end glide track connecting the lower and upper glide tracks.
2. Description of the Prior Art
U.S. Pat. Nos. 4,014,389 and 4,614,238 and DE 31 51 652, whose disclosures are incorporated herein by way of reference, disclose arrangements of this type, wherein an endless ballast conveyor chain is revolved around a track to excavate the ballast supporting the track and to convey the excavated ballast. The chain is guided by a transverse guide section in contact with the ballast bed during operation and longitudinal guide sections linked to the ends of the transverse guide section by joints. Guide rollers extending coaxially with the axes of the joints deflect the excavating chain from the transverse to the longitudinal guide sections. The pivotal connection between the guide sections is necessary to enable the excavating chain to be slightly displaced relative to the track. This facilitates work in restricted areas of the track. It also makes it possible to elongate the transverse guide section for operation in widened track switches. Since efficient ballast cleaning machines require the ballast excavating chain to be subjected to a tensile force of about 100 kilonewton during excavation, the amply lubricated guide rollers are subject to extremely high loads and must be frequently replaced.